Responsible Builder: When Your House Encroaches on a Non-Buildable Zone

Imagine: you have just bought a plot of land in Vallauris, with a view of the potters' hills. You dream of building your house there, you entrust the work to a reputable builder. The walls go up, the roof is installed... but then a neighbour alerts you: part of your beautiful house might be encroaching on a non-buildable zone. Your nightmare begins. Who is liable? The builder who sited the house? The surveyor who prepared the plan? You, the owner?

This situation, unfortunately common on the Côte d'Azur where land is valuable and planning rules are strict, has found a clear answer in a decision of the Cour de cassation. But what exactly does this change for you, as an owner, tenant, or real estate professional?

The highest French court has ruled: regardless of how the contract is classified, the builder owes you an obligation of advice and an obligation of result. In short, if they site your house incorrectly, even partially in a non-buildable zone, they are liable. Let's see what this means concretely for your property projects.

The facts: a story as it happens every day

Mr Martin, owner of a plot of land in Vallauris, decides to build his dream house. He signs a contract with the company Bâtir Plus, a local builder. Everything seems to proceed normally: the builder consults a survey plan (a document that precisely delimits a plot of land) to site the house. The work progresses, the house takes shape.

But then, as the handover approaches (the act by which the client accepts the works), a problem arises. A neighbour, Mr Dubois, points out that the west wing of the house appears to extend into a zone classified as non-buildable. Panic ensues! Mr Martin calls in an expert surveyor who confirms: approximately 15 m² of his house are indeed sited in a non-buildable zone.

The owner then turns against the builder: "You have sited my house incorrectly!" The builder defends himself: "The survey plan was erroneous, it's not my fault!" The legal battle begins. Mr Martin sues Bâtir Plus in court, demanding demolition of the illegal part and damages. The builder, for his part, tries to shift the blame to the surveyor who prepared the plan.

The first judges partially rule in favour of Mr Martin, but the builder appeals. The appeal court modifies the judgment, considering that liability is not so clear. Finally, the case reaches the Cour de cassation, which will settle this dispute that has become exemplary.

The court's reasoning — dissected

The magistrates of the Cour de cassation analysed the situation with great legal precision. Their reasoning rests on a fundamental principle: the builder's obligation of advice and obligation of result. But what exactly does this mean?

The obligation of advice means that the builder must inform you of risks, alternatives, technical and regulatory constraints. The obligation of result is stronger: the builder commits to delivering a house that conforms to what was planned, without defects. These obligations stem notably from Article 1240 of the Civil Code (which obliges compensation for damage caused by one's fault) and from prior case law on contracts for work.

In this case, the Court considered that, regardless of the classification of the contract (contract for work, mandate, etc.), the builder was bound by these two obligations. In other words, no matter what the contract is called, the builder must advise their client correctly and deliver a conforming result.

The builder had used a survey plan to site the house. However, this plan contained an erroneous boundary between buildable and non-buildable zones. The Court held that the builder, as a professional, should have verified the reliability of the documents they used. They could not simply blindly follow a potentially incorrect plan. By leaving the question of the plan's validity undetermined, they had failed in their obligation of advice.

Note, however: the Court specified that the company that had prepared the survey plan was not implicated in this proceeding. This does not mean they would have no liability, but simply that they were not a party to the dispute between Mr Martin and the builder. The builder could potentially take action against them in another proceeding.

This reasoning confirms consistent case law: builders have strong liability, notably before the handover of works. This is an important evolution to protect individuals against professionals.

What this changes for you — concretely

If you are an owner and you are having a house built, this decision protects you more. Concretely, if your builder sites your house incorrectly, even partially in a non-buildable zone, you can demand compensation. undefined, I have encountered cases where owners in Mandelieu found themselves with swimming pools or extensions in non-buildable zones: this decision gives them strong arguments.

The consequences can be severe. Imagine: in Mandelieu, a 150 m² house with 20 m² in a non-buildable zone. The solutions? Either demolish the illegal part (cost: €15,000 to €30,000 depending on the case), or regularise if possible (a complex administrative process, often refused). In both cases, the value of your property decreases. With this decision, you can claim these losses from the builder.

If you are a tenant of a house that is incorrectly sited, the situation is different. You are not directly concerned by this decision, but it can impact your lease. If demolition works are ordered, your accommodation could become partially uninhabitable. You could then request a rent reduction or even terminate the lease.

For real estate professionals (estate agents, developers), this decision reinforces the need for rigorous checks. Selling or promoting a property partially in a non-buildable zone exposes you to actions for latent defects. How to react? Before any transaction, demand an operational planning certificate and a recent boundary plan.

Time limits are crucial. The action against the builder is subject to a limitation period of 10 years from the handover of works (Article 1792 of the Civil Code). But note: if the defect was latent, the period can be longer. In all cases, act quickly as soon as you suspect a problem.

Four tips to avoid this type of dispute

• Demand an official boundary plan before work begins: do not settle for a simple sketch. A chartered surveyor must prepare a certified plan, with precise marking of boundaries and buildable zones. Average cost on the Côte d'Azur: €1,500 to €3,000 depending on complexity.
• Personally check the planning certificate: request an operational planning certificate (not just informational) from the town hall. This document specifies the rules applicable to your land, including buildable zones. Do not delegate this check to the builder alone.
• Include a specific clause in your building contract: specify that the builder guarantees siting in conformity with planning rules and commits to verifying all technical documents. This clause strengthens your protection in case of dispute.
• Attend the staking out (marking on the ground of construction limits): be present when the builder marks the location of your future house. Compare with the boundary plan. If something seems suspicious, stop the works immediately and consult an expert.

In-depth analysis: related case law and developments

This decision fits into a jurisprudential trend favourable to clients. Already in 2006, the Cour de cassation had held in a ruling (No. 05-10.305) that an architect was liable for not verifying the buildability of a plot of land. What few people know is that judges are progressively extending this verification obligation to all construction professionals.

A prior divergent decision (1998 ruling) had somewhat protected builders, considering they could rely on official documents. The 2010 decision thus marks a partial reversal: now, the builder must exercise active control, not just follow documents.

For the future, this trend should be confirmed. Courts are increasingly demanding of professionals, considering they have technical expertise that justifies heightened liability. This means that, if you are a builder, you will need to strengthen your control teams and verification procedures.

In the Grasse jurisdiction, courts apply this case law strictly. I have myself pleaded before the Grasse tribunal judiciaire in cases where judges have condemned builders for incorrect siting, precisely based on this obligation of advice and result.

What you must absolutely remember

1. The builder is always liable for the correct siting of your house, even if it is a third-party document (like a survey plan) that is erroneous. They must verify what they use.

2. The obligation is twofold: advice AND result. The builder must inform you of risks (advice) and deliver a conforming house (result).

3. Act before the handover of works. This is the key moment: once the handover is signed, it is harder to challenge the siting.

4. The limitation periods are 10 years from handover, but consult a solicitor quickly if you have any doubt.

5. The cost of a siting error can be colossal: between demolition, loss of property value, and legal fees, it can easily exceed €50,000 on the Côte d'Azur.

Do you find yourself in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of proceedings — and often much more. Book an appointment →